Mercury contamination in Lavras do Sul, south Brazil: a legacy from past and recent gold mining

Mercury concentrations at a historically mercury-contaminated site in KwaZulu-Natal (South Africa)

“…The observations in this study are similar to what has been reported for other historically Hg-contaminated sites (Pestana and Formoso 2003;Pereira et al 2009), and supports the notion that historically Hg-contaminated sites should remain in its existing condition, and that routine monitoring of water, sediment and biota can be used as a proxy for assessing the extent to which resuspended Hg that is reintroduced to the water column becomes bioavailable to biota. Such routine monitoring programmes are valuable for decision-making with regards to historically Hg-contaminated sites and its impacts to the aquatic environment.…”

“…Regardless, this study provided a "snapshot" of the TotHg and MeHg concentrations in water, sediment, invertebrates and fish collected in the Umgeni and Mngceweni rivers of KwaZulu-Natal. The results suggest that the historically Hg-contaminated Mngceweni River still represents a potential Hg source to the surrounding area, similar to what has previously been observed at other historically Hg-contaminated sites in Europe (Berzas Nevado et al 2003;Regnell et al 2009), USA (Thomas et al 2002) and South America (Pestana and Formoso 2003). The relatively high Hg concentrations measured in sediment and fish (particularly downstream of the plant) render this site a potential Hg "hotspot".…”

“…Residual Hg remobilization from sediment appears to be minimal, although as expected, it is elevated during the wet season thereby making it more bioavailable for uptake in the aquatic food chain. Further remediation of Hg is not recommended for the Mngceweni River, as any dredging processes will resuspend Hg into the water column, as reported by others (Pestana and Formoso 2003;Bravo et al 2009;Knott et al 2009;Urban et al 2010). However, a routine monitoring programme of sediment and fish is recommended, similar to what has been previously recommended for this area (Barrat and Combrink 2002;Papu-Zamxaka et al 2010).…”

Distribution and mobility of mercury in soils of a gold mining region, Cuyuni river basin, Venezuela

“…These elevated contents are similar to those found in other gold mining areas in Brazil (Gonçalves et al, 2000;Pestana and Formoso, 2003) and in the Philippines (Appleton et al, 2006), where similar methods of amalgamation gold recovery are carried out. Moreover, in other small Hg (cinnabar) mine locations, such as those of the area of Podljubelj (northwestern Slovenia) and the area of Türkönü (eastern Turkey), mining affected soils show total Hg contents in similar 0.35e244 mg kg À1 (Tersic et al, 2009) and 12.1e41.6 mg kg À1 (Gemici and Tarcan, 2007) ranges respectively.…”

“…Such values are very high with respect to the corresponding total Hg contents, representing a fraction in the 86.66e92% range of total Hg. A similar Hg fractionation in gold mining soils has been reported in Brazil (Pestana and Formoso, 2003), where the Hg 0 fraction represents 82e83% of total Hg. However, this Hg 0 fraction seems to be high in comparison with those reported for cinnabar mining districts.…”